Fulfilled immediately afterwards in His transfiguration on the mountain with Moses and Elijah, seen by Peter, James and John.
There is no evidence that they ever proselytized any of the cities of Judah/Southern Israel in their day.
The "this [
literally, the same] generation" refers to the generation of the fig tree putting forth leaves, which is End Times.
Which
everyone, living and dead, will see at the Parousia and following resurrection of the dead: "
all in the graves will hear His voice and come forth..." John 5:28-29
The Baptist was speaking to the hardhearted Jews. No mention here about anything otherwise.
None of the above quotes prove that the biblical End Times ended in or by
70 AD. One must read such a presumption into them by a pre-determined bias.
However, Daniel 11:40ff., and many many passages in Revelation, as well as Jesus' own words about such things as all the tribes of the earth seeing Him coming on the clouds of heaven, and the sign of Son of Man appearing in heaven, and the time of trouble such as never was nor shall be again -- none of these prophecies can be credibly claimed to have been fulfilled before our day.